In the process of producing a semiconductor device such as IC and LSI, microfabrication by lithography using a photoresist composition has been conventionally performed. In recent years, with the increase in the integration degree of an integrated circuit, formation of an ultrafine pattern in the sub-micron or quarter-micron region is required, and in turn, the exposure wavelength tends to become shorter, for example, from g line to i line or further to KrF excimer laser light. In addition to the excimer laser light, development of lithography using an electron beam, an X-ray or EUV light is also being pursued at present.
Such electron beam, X-ray or EUV lithography is positioned as a next-generation or next-next-generation pattern formation technology, and a resist composition having high sensitivity and high resolution is demanded.
In particular, the elevation of sensitivity is a very important issue for shortening the wafer processing time, but when higher sensitivity is pursued, the pattern profile or resolution indicated by a limiting resolution line width is deteriorated, and it is strongly desired to develop a resist composition satisfying all of these properties at the same time.
High sensitivity is in a trade-off relationship with high resolution and good pattern profile, and the matter of importance is how to satisfy these properties at the same time.
The actinic ray-sensitive or radiation-sensitive composition generally includes “a positive resist composition” used in a pattern forming method of forming a pattern by using a resin sparingly soluble or insoluble in an alkali developer and making the exposed area soluble for an alkali developer by the exposure to radiation, and “a negative resist composition” used in a pattern forming method of forming a pattern by using a resin soluble in an alkali developer and making the exposed area sparingly soluble or insoluble for an alkali developer by the exposure to radiation.
As the actinic ray-sensitive or radiation-sensitive composition suitable for such a lithography process using an electron beam, X-ray or EUV light, a chemical amplification positive resist composition utilizing mainly an acid catalyst reaction is studied from the standpoint of elevating the sensitivity, and a chemical amplification positive resist composition composed of a phenolic resin as the main component, which is insoluble or sparingly soluble in an alkali developer and has a property of becoming soluble in an alkali developer under an action of acid (hereinafter, simply referred to as a phenolic acid-decomposable resin), and an acid generator, is being effectively used.
Also, for providing an actinic ray-sensitive or radiation-sensitive composition significantly enhanced in the photosensitization speed by amplifying a photochemical reaction, it is known to use, together with the above-described acid generator, an acid-increasing agent capable of newly generating an acid (e.g., sulfonic acid) by an action of the acid generated from the acid generator (see, for example, Patent Document 2).
However, the acid-increasing agent known at present is bad in the aging stability, and this problem greatly affects the performance of a resist composition and is required to be solved.
As for the acid generator that is the main constituent component of the chemical amplification resist, a triphenylsulfonium salt is generally known.
In addition, for providing a chemical amplification resist composition significantly enhanced in the photosensitization speed by amplifying a photochemical reaction, it is known to use, together with the above-described acid generator, an acid-increasing agent capable of newly generating an acid by an action of the acid generated from the acid generator (see, for example, Patent Document 1).
As the acid-increasing agent, an acid-increasing agent having a structure where a sulfonyloxy group and a hydroxy group are coupled through three carbon atoms, is known. For example, in Patent Document 2 and Non-Patent Document 1, an acid-increasing agent having such a specific structure is used in a positive chemical amplification resist composition, and in Patent Document 3, a positive chemical amplification resist composition containing a resin having such a specific structure is disclosed.
Furthermore, the microfabrication by a resist composition is not only used directly for the production of an integrated circuit but also, in recent years, applied to the production or the like of a so-called imprint mold structure (for example, Patent Document 4 and Non-Patent Document 2). Therefore, it becomes an important issue to satisfy all of high sensitivity, high resolution (for example, high resolving power, excellent pattern profile and small line edge roughness (LER)), good dry etching resistance, excellent scum properties, and excellent aging stability at the same time.